TECHNICAL PAPER Understanding HPHT Riser Design Limits for Deep and Ultra Deep Water P. Padelopoulos, R. Thethi, W. Mo World Oil HPHT Drilling Conference September 2019
TECHNICAL PAPER
Understanding HPHT Riser
Design Limits for Deep and
Ultra Deep Water
P. Padelopoulos, R. Thethi, W. Mo
World Oil HPHT Drilling Conference September 2019
Learn more at www.2hoffshore.com
Understanding HPHT Riser Design Limits for Deep and Ultra Deep Water
Peter Padelopoulos, Weihua Mo, Ricky Thethi
Snr Principal Engineer
2H Offshore
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Agenda
• Introduction
• Riser Configurations
• HPHT Riser Design Drivers
• Technology Readiness Status Heat Maps
• Summary
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Introduction
• Operators are looking to drill and develop deep water wells with high pressure >15ksi and high temperature >300°F
• Designing for HPHT conditions presents a number of engineering challenges which is stretching the conventional subsea technologies to their limits – Pipe manufacture reliability– Riser payload for installation and on host vessel
• The feasibility of 8" & 10" production risers subjected to HPHT conditions assessed on a quick ‘look-up’ technology readiness status chart are summarized in this presentation
Image Ref: OTC-28624-MS HPHT Riser Technology Challenges
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Example of Steel Catenary Riser (SCR) Example of Steel Lazy Wave Riser (SLWR)
Riser Configuration - Catenary
• Catenary riser configurations can consist of steel or flexible pipe construction
• Configuration may comprise of a simple catenary or lazy wave
• Risers interface with semi-submersible, Spars, TLPs, FPSO’s
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Tensioner System
Lower Riser System
Upper Riser System
Riser Configuration – SVIR• Single Vertical Import Risers
(SVIR) – Single or Dual Casing Tensioned via a Tensioner System
• Comprise of multiple interfaces and wide range of hardware packages
• Shell Perdido Spar, GoM, 8,000 ft water depth
• Chevron Genesis Spar (Export), 2,614 ft water depth
• Exxon Marimba (Pipe-in-Pipe with mechanical connectors) tied back to Kizomba TLP, West Africa, 3,900 ft water depth
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Riser Configuration – FSHR
• Free Standing Hybrid Risers – Dual or Single Casing Tensioned via Buoyancy Tank
• To date FSHRs globally consist of a welded construction. Alternative approach to use high strength steel with non-weldable mechanical connectors
• Petrobars Cascade Chinook, GoM, 8,190 ft water depth
• Exxon Kizomba B (Pipe-in Pipe), West Africa, up to 4,200 ft water depth
• Interface with high motion vessels such as FPSO’s, shallow draft semi-submersibles
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HPHT Riser Design Drivers – Global Design Parameters
• High pressure and high temperature
• Riser diameter – increase results in thicker wall
• Vessel motions - draft, strength, fatigue motions, hull VIM
• Water depth - shallower impacts TDP, deeper impacts the top
• Sour service – Knock down factors
• Acid stimulation - spent acid flowing back through SCR
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HPHT Riser Design Drivers – Steel Pipe Wall Thickness Considerations
• Wall thickness to be per 30 CFR 250.1002
• Material strength de-rated due to temperature
• Per NTL 2009-G28, API RP 1111 can be used to calculate wall thickness due to internal pressure– API RP 1111 specifies to use
ASME B31.8 for de-rating
• Temperature de-rating for actual material is difficult to come by without project specific data
48.0
50.0
52.0
54.0
56.0
58.0
60.0
62.0
64.0
66.0
50 75 100 125 150 175 200 225 250 275 300 325 350 375 400
Yie
ld S
tre
ng
th (
ksi)
Temperature (°F)
STEEL YIELD STRENGTH TEMPERATURE DERATINGAPI 5L X65 Steel (SMYS=65.3ksi)
DNVGL-ST-F201 (2018) API-RP-17G (2006) ASME II Part D (2015) ASME B31.8 (2007)
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HPHT Riser Design Drivers – Steel Pipe Wall Thickness Considerations
• To minimize wall thickness the following can be utilized:– Select appropriate temperature de-rating factor– Include NTL 2009-G28 to reduce surface pressure
by using gas head– API RP 1111, Appendix B, use 0.5 burst co-efficient
instead of 0.45. A number of requirements are stipulated to be conducted in production; • Full-length helical UT inspection of each length,
including UT wall thickness measurement• Specified minimum wall thickness greater than or
equal to 90 % of nominal• Mechanical properties to be tested with an
acceptable quality level = 0.10 %• Burst testing Image Ref: OTC-28624-MS HPHT Riser
Technology Challenges
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HPHT Riser Design Drivers – Steel Pipe Wall Thickness
• Challenge and limitations associated with the large wall thicknesses pipe
– Optimizing the micro alloy composition to achieve required mechanical properties
– Meeting hardness values for sour service applications
– Pipe inspection and quality control of production of heavy wall pipe
– Excessive hydrostatic pressures and effect on pipe mills equipment/capabilities
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
2.00
2.20
15,000 psiX65
17,500 psiX65
20,000 psiX65
15,000 psiX70
17,500 psiX70
20,000 psiX70
Wa
ll T
hic
kn
ess (
inch
)
10 inch OD, Wall Thickness Sizing for Different Ranges of Design Pressures and Temperatures
250 °F 300 °F 350 °F
Existing Technology Limit = 1.9inch
Ref: OTC-28624-MS HPHT Riser Technology Challenges
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HPHT Riser Design Drivers – Flexible Pipe Limitations
• Internal pressure capacity defined by Pressure*ID
• Flexibles under 6inch, 20ksi and up to 300°F qualified
• Ultra deep water flexibles prone to collapse restrictions, thus eliminating flexible risers– Currently 10’’ at 6,890ft for
sour service
• Multiple smaller lines would be required for FSHR and SVIRs– Issues with top of riser offtake
design
– Pigging multiple linesNote: 100MPa = 14.5ksi, 140MPa = 20ksiRef: 2010 - Deepwater Production Riser Systems & Components, Offshore Magazine
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HPHT Riser Design Drivers –Installation Vessel Limitations
Ref: OTC-28624-MS HPHT Riser Technology Challenges
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
5000 7500 10000 12500
Ris
er
To
p T
en
sio
n (
kip
)
Water Depth (ft)
INSTALLATION TENSION REQUIREMENTS vs WATER DEPTHX65 Production Risers, 350 °F Design Temperature, 12° Hang-off Angle,
Riser Filled with Seawater
8inch OD-15ksi 8inch OD-17.5ksi 8inch OD-20ksi
10inch OD-15ksi 10inch OD-17.5ksi 10inch OD-20ksi
Reel lay tension limit = ~2,200kip
S-Lay tension limit = ~3,300kip
J-Lay tension limit = ~4,400kip
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HPHT Riser Design Drivers – Riser Components
• Flexible Joints have been used up to approximately 13 ksi design pressure and 250 °F design temperature. – Concern with elastomeric elements at higher temperatures
• Steel Tapered Stress Joint could be challenging due to limits on forging length, wall thickness, weight restrictions and loads into vessel
• Titanium Stress Joint should not be directly injected with fresh hydrofluoric (HF) acid. HF spent acid flowback tests from multiple operating fields confirm no attack on titanium TSJs
• As an alternative to thick walled steel pipe alternative technology such as composite pipe may be considered, although no track record for production risers– Lightweight, high strength, pressure upto 20ksi and temperatures to 300°F
– Magma Global (m-pipe) and Airborne
Flexible Joint
Composite Pipe
Tapered Stress Joint
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Technology Readiness Status Heat Maps - SCRs
• Heat map10,000ft*
3 3 3 3 3 3 3 2 3 1 3 1 3 1 3 1 3 1 3 1 2 1 2 1
8,000ft*
4 3 4 3 4 3 4 2 3 1 3 1 3 1 3 1 3 1 3 1 2 1 2 1
6,000ft*
4 3 4 3 4 3 4 2 3 1 3 1 3 1 3 1 3 1 3 1 2 1 2 1
4,000ft†
4 3 4 3 4 3 4 2 3 1 3 1 3 1 3 1 3 1 3 1 2 1 2 1
3,000ft†
4 3 4 3 4 3 4 2 3 1 3 1 3 1 3 1 3 1 3 1 2 1 2 1
8" 10" 8" 10" 8" 10" 8" 10" 8" 10" 8" 10" 8" 10" 8" 10" 8" 10" 8" 10" 8" 10" 8" 10"
High Uncertainty to Pass Qualification Qualification Stretch Qualified (Not Used) Field Proven
* Reaches water depth limits of current pipe lay vessels (9,800ft) and/or tension capacity limit (depending on pipe lay methods)
† Potential fatigue issues at touch down zone of SCR, especially in riser pipe inner diameter due to sour service
Key Technology Limitations: • Pipe wall thickness • Weldability • Sour Service
Based on Pipe Wall Thickness and Weldability
250°F 300°F
Steel Grade X65 for High Pressure High Temperature Offshore Risers
400°F
15,000psi 17,500psi 20,000psi
Technology Readiness Status – Steel Catenary Riser / Steel Lazy Wave Riser
350°F 400°F 250°F 300°F 350°F250°F 300°F 350°F 400°F
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Technology Readiness Status Heat Maps – Flexible Riser
• Heat map
10,000ft1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
8,000ft1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
6,000ft3 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
4,000ft3 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
3,000ft3 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
Bore ID 5" 7" 5" 7" 5" 7" 5" 7" 5" 7" 5" 7" 5" 7" 5" 7" 5" 7" 5" 7" 5" 7" 5" 7"
High Uncertainty to Pass Qualification Qualification Stretch Qualified (Not Used) Field Proven
* Potentially one or two replacement campaigns over 20+ field life span
Key Technology Limitations: • Internal pressure capacity • Design temperature limit • Collapse water depth
350°F 400°F
15,000psi 17,500psi 20,000psi
300°F 350°F 400°F 250°F 300°F250°F 300°F 350°F 400°F 250°F
Technology Readiness Status – Flexible Production RiserBased on Internal Pressure Capacity and Temperature Limit
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Technology Readiness Status Heat Maps – FHSR
• Heat map
10,000ft3 3 3 3 1 1 1 1 3 1 3 1 1 1 1 1 3 1 3 1 1 1 1 1
8,000ft *3
*3 1 1 1 1 3 1 3 1 1 1 1 1 3 1 3 1 1 1 1 1
6,000ft *3
*3 1 1 1 1 3 1 3 1 1 1 1 1 3 1 3 1 1 1 1 1
4,000ft *3
*3 1 1 1 1 3 1 3 1 1 1 1 1 3 1 3 1 1 1 1 1
3,000ft *3
*3 1 1 1 1 3 1 3 1 1 1 1 1 3 1 3 1 1 1 1 1
8" 10" 8" 10" 8" 10" 8" 10" 8" 10" 8" 10" 8" 10" 8" 10" 8" 10" 8" 10" 8" 10" 8" 10"
High Uncertainty to Pass Qualification Qualification Stretch Qualified (Not Used) Field Proven
* Multiple flexible jumpers required to meet the pressure rating requirement and provide required flow area
† Envelope may be expanded with the use of non-welded premium connectors
Key Technology Limitations: • Non-weldable mechanical connector • Surface jumper assembly • Subsea rigid jumper assembly
15,000psi 17,500psi 20,000psi
Technology Readiness Status – Free Standing Hybrid RisersBased on Flexible Surface Jumper Limits and Welding X65 Steel Pipe Limits
250°F 300°F 350°F 400°F 250°F 300°F 350°F 400°F 250°F 300°F 350°F 400°F
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Technology Readiness Status Heat Maps – SVIR
• Heat map
10,000ft3 3 3 3 1 1 1 1 2 2 2 2 1 1 1 1 2 2 2 2 1 1 1 1
8,000ft3 3 3 3 1 1 1 1 2 2 2 2 1 1 1 1 2 2 2 2 1 1 1 1
6,000ft3 3 3 3 1 1 1 1 2 2 2 2 1 1 1 1 2 2 2 2 1 1 1 1
4,000ft3 3 3 3 1 1 1 1 2 2 2 2 1 1 1 1 2 2 2 2 1 1 1 1
3,000ft3 3 3 3 1 1 1 1 2 2 2 2 1 1 1 1 2 2 2 2 1 1 1 1
8" 10" 8" 10" 8" 10" 8" 10" 8" 10" 8" 10" 8" 10" 8" 10" 8" 10" 8" 10" 8" 10" 8" 10"
High Uncertainty to Pass Qualification Qualification Stretch Qualified (Not Used) Field Proven
* Deepwater SVIR system for mild sour service and with 17.5ksi and beyond is a technology challenge for most SVIR components.
Key Technology Limitations: • Non-weldable mechanical connector • Flanges • Surface Jumper Assembly • • Subsea Rigid Jumper Assembly • Tieback Connector
15,000psi 17,500psi* 20,000psi*
Technology Readiness Status – Single Vertical Import RiserBased on SVIR Component Technology Readiness
250°F 300°F 350°F 400°F 250°F 300°F 350°F 400°F 250°F 300°F 350°F 400°F
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Summary
• Riser design for HPHT conditions is challenging
• The key driver is riser wall thickness and impact on manufacturing reliability, installation and payload on host vessel
• NTL 2009-G28 and API RP 1111, Appendix B should be utilized for riser wall thickness design
• SCRs or SLWR offer the most feasible riser configuration for HPHT conditions
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Questions
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